Intonational variation in the British Isles

Transcription

1 Intonational variation in the British Isles Introduction and background Esther Grabe Phonetics Laboratory University of Oxford Intonation varies with dialect. in the British Isles, we find a number of different intonation systems. The same utterance, spoken with exactly the same intention, can have different intonation patterns in different dialects. Dialect intonation in the British Isles has been investigated extensively. But in the past, limitations on recording facilities have made multiple comparisons of dialects difficult. Studies have been mono-dialectal, data not comparable. Studies rarely quantitative. Intonational variation in the British Isles ESRC funded research project Cambridge and Oxford (Grabe, Nolan, Post) Quantitative modelling of intonational variation in the British Isles ESRC funded research project Oxford (Grabe, Kochanski, Coleman)

2 Aims Outputs to collect a corpus of speech data from a number of English dialects, to collect directly comparable data, to carry out linguistic and quantitative analyses. The IViE Corpus. An intonation transcription system. Descriptive publications. The IViE corpus Speech database intended to give a flavour of intonational variation. Designed to illustrate some of the effects of dialect, style, speaker and gender. 36 hours of speech, available on the internet, free. Seven urban dialects London ( Jamaican ) Cambridge Leeds Bradford (Punjabi) Newcastle Belfast Dublin Five speaking styles Sentences Read text Retold text Map task Free conversation Twelve speakers from each dialect, six male and six female. 6 years of age, attended same secondary school, parents born in area. Four hours of speech transcribed: words, prominent syllables, intonation. Samples transcribed from each of the five styles. ~ 7200 intonation phrases. ~ 4400 accents. Subsection on the internet. 2

3 Main within-dialect finding Analysis of transcriptions Considerable variation within and across speakers. On identical texts and in identical contexts, speakers produce a range of contours. Main between-dialect finding Differences involve usage and frequency of contours rather than specific contour shapes. Transcriptions Two-tone using H, L, *, %, H = pitch maximum, L = pitch minimum, Distributions overlapped across dialects and speakers. * = stressed syllable, % means end of intonation phrase. Example Nuclear Accent distribution in Wh-Questions Graph showing distribution of nuclear accents in wh-questions produced on identical texts, L*H % in identical tasks, Bradford Dublin Bradford by speaker groups controlled for Cambridge L* H% dialect, age and peer-group. H*L % H* H% Belfast Belfast Newcastle London Leeds L*H H% H*L H% 3

4 Next slide Distribution of all nuclear accents in the IViE sentence data. Data in following table simplified Various sentence types, 74 sentences. Distributions of accent shapes within and between dialects overlap. over 0% over 40% over 80% accent accounts for more than 0% of total accent accounts for more than 40% of total accent accounts for more than 80% of total over 0% over 40% over 80% Current project London Cambr. Bradf. Leeds Newcast. Belfast Dublin H*L % H*L H% Quantitative modelling of intonational variation in the British Isles H* H% L*H % L*H H% L*H L% Exploiting the transcriptions. Mapping between transcription and acoustics. L* H% Remainder of the talk Mapping between transcriptions and acoustics. Computational-mathematical modelling of f 0 patterns associated with nuclear accents. The question The linguistic transcriptions allege that there are 7 different nuclear accents in the IViE data. Is there quantitative support for this assertion? 4

5 Materials 74 read sentences; context-free. Experimental investigation Four sentence types: declaratives, wh-questions, yes/no questions, declarative questions. Six male and six female speakers from each dialect. Nuclear accent label Stylisation Description following the British tradition Distribution of nuclear accents in the sentences Accents Tokens. H*L % 2. H*L H% 3. H* H% 4. L*H % 5. L*H H% Fall Fall-rise High rise Rise-plateau Rise H*L % L*H % H*L H% L*H H% H* H% L* H% fall rise-plateau fall-rise rise high rise late rise L* H% Late rise L*H L% rise-plateau-fall 9 7. L*H L% Rise-plateau-fall NB: collapsed over dialects 70 The question Polynomial modelling Can we find quantitative support for the existence of 7 different nuclear accents? Common mathematical approach to the description of curves. Method Models produce a hierarchy of descriptions of increasing complexity and accuracy. Orthogonal-polynomial modelling of f 0 contours associated with nuclear accents. 5

6 First step in the combination of polynomial equations and linguistic descriptions of prosody: Andruski and Costello (2004). Explored small differences in f 0 contours of three low falling tones in Green Mong. Green Mong has seven tones, three are quite similar in shape: low falling but differ in phonation type. Andruski and Costello asked: could f0 contour shape alone be used to identify the tones? (Language spoken in South-East Asia in the region surrounding the Southern Chinese border.) Used polynomial equations to generate quantitative descriptions of the slope and the shape of the curvature of the three tones. Subsequent statistical analyses: Introduction to polynomial modelling the three tones can be discriminated above chance level on the basis of slope and shape. Orthogonal polynomials Mathematical functions that describe curves of increasing complexity. Polynomial Mathematical expression involving a sum of powers in one or more variables multiplied by constants. a 2 x 2 + a x + a 0 6

7 Orthogonal Each term of the equation describes one aspect of the wiggliness of the curve. P 0 P Legendre polynomials P 2 P 3 Type of orthogonal function used, referred to by the letter P. Every data point is treated equally. P 4 P 5.00 Added together, Legendre Polynomials can model contour shapes such as f 0 traces. Normalised frequency He is on the lilo -.00 Normalised time.00 Original The model reduces the complexity of the f 0 contour to six coefficients Many contours require fewer coefficients. Model P add 0 P Contours appear to be very complex but mathematically, they are relatively simple

8 Analysis was carried out with a set of custom-written computer scripts. Our analysis Description of analysis and instructions for how to carry out modelling in MS Excel: Grabe, Kochanski and Coleman (accepted, Language and Speech) We used polynomial equations to describe. the average and 2. the slope of each f 0 contour, and two kinds of curvature. a parabola shape and 2. a wave shape. Each of the 70 nuclear accents was modelled separately. Results shown are averages for each accent types. Example: results for two rising accents H* H% L*H H% Results c c 0 c c 2 c 3 c 0 c c 2 c 3 average slope parabola wave 8

9 H* H% H*L % H*L H% L*H L% L*H % L* H% L*H H% Question Are the polynomial models associated with each of the seven accents statistically different? MANOVA Dependent variables AVERAGE (c 0 ) SLOPE (c ) PARABOLA (c 2 ) WAVE (c 3 ) Independent variable NUCLEAR ACCENT TYPE highly significant AVERAGE p < 0.00 SLOPE p < 0.00 PARABOLA p < 0.00 WAVE p < 0.00 NUCLEAR ACCENT TYPE Post-hoc tests (Tukey) 7 of the 2 accent pairs highly significantly different in one or more coefficients. A further two pairs differed at at p <. The late rise L* H% (London ) did not differ significantly from L*H % (rise plateau, especially Belfast ) and L*H H% (rise, all dialects ). 9

10 The analysis also showed: three coefficients would have been sufficient to distinguish between the nuclear accents. Finally, we reconstructed average f 0 patterns for each accent shape, using the coefficients. We found significant differences between contours in the fourth, but the information was redundant. The reconstructed f 0 models summarise the salient characteristics of each accent type. Superimposed: one original, normalised f 0 trace from the corpus. Traces show: the polynomial models despite being an average are representative of the data. H*L,% H*,H% H* H% - + H*L,H% L*H,L% H*L % H*L H% L*H L% L*H,% L*,H% L*H % L* H% Model Original f 0 trace L*H,H% L*H H% The models did not distinguish between the late rise L*H % Discussion and two other rising accents Rise-plateau L* H% Rise L*H H%. 0

11 Data sparsity? Neutralisation? 2 tokens late rise L* H% 44 tokens fall H*L % Nuclear accents produced on two-syllable words with initial stress such as limo. Accented syllable followed by only one syllable. Not a lot of room for realisation of nuclear accent shape. Nuclear accent distinctions can be observed more clearly when accented syllable is followed by more syllables. Conclusion More room for realisation of distinction between patterns. Additional work required. Polynomial modelling can be of value to intonational phonologists. The combination of hand-labels and polynomial models can also be of value to speech technologists. Hand-labels can be supported by empirical acoustic evidence. Need empirically tested and implementable models of intonation filtered by linguistic insights.

12 Our approach may help in the building of bridges between intonational phonologists and speech technologists. Thank you for your attention 2